But people willing to venture out in person will save some serious money: they paid $31, compared to the $53 online shoppers shelled out. Shipping fees were responsible for about $10 of that differential, but even the per-item costs online were higher.

Why? It’s all about convenience. People in a hurry to get their shopping done typically don’t mind paying more to do it. What’s more, physical stores are often willing to lose money on cheaper things like school supplies to get people in the door — where they’ll hopefully buy additional items they didn’t even know they wanted.